Why can't the United States go bankrupt? A.) The government can issue new bonds to pay off old bonds
B.) We owe part of the debt to ourselves
C.) All of the possible choices
D.) The government never has to give up purchasing power because taxes collected are only transferred to other groups

I'm not completely sure if this is right but I believe it's C..

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.